Meet John, who was born on 25 April, 1916.
He learned to walk on his hands while he was in the army and could go from the corner of a football pitch to the goal posts - and now enjoys doing it underwater during his daily swim.
You don't have to be 100 to get involved in International Handstand Day though! Whether you are on a beach, in a park, on a dance floor or doing your house chores you can take part.
On Saturday, 25 June people around the UK and around the globe will be showing off their handstands for the world to see.